CentOS 5 Networking :: How To Configure NTPD Correctly With Firewall

Jan 21, 2011

I am running a centOS 5.5 server and can't synchronize with time servers via ntpd. My server sits behind a firewall with only port 80 open and I suspect this is the issue. Do I need to open other ports to connect to the time servers at [URL]?

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CentOS 5 Networking :: GIPTables Firewall - How To Configure It

Jan 24, 2010

I'm stuck at server with OpenNA installed, which has no relation with CentOS but If anyone knows GIPTABLES firewall to point me somewhere I can get configuring.I need to open 2 custom ports but I just can't get it to work.

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Networking :: Install And Configure Hardware Firewall In Centos?

Feb 24, 2011

I have centos with software firewall enable , but i want to set up hardware firewall can anybody guide how to install and configure hardware firewall in centos

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CentOS 5 :: Starting Ntpd: Ntpd: Error While Loading Shared Libraries: Libm.so.6

Mar 30, 2011

[root@espeed log]# /etc/init.d/ntpd start
Starting ntpd: ntpd: error while loading shared libraries: libm.so.6: cannot open shared object file: No such file or directory
[root@espeed log]# ldd /usr/sbin/ntpd
linux-gate.so.1 => (0x00786000)
libm.so.6 => /lib/libm.so.6 (0x0059d000)

[code]....

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CentOS 5 Networking :: Configure Firewall - Allow And Forward All Traffic On Eth0 And Block All Traffic On Eth1 Except Ssh Ping

Sep 29, 2010

I need to set up my centOS computer as a firewall in my home network. Ive got 2 interfaces, eth0 and eth1. I want to allow and forward all traffic on eth0 and block all traffic on eth1 except ssh, ping(icmp) and DNS. How do I do this? Ive tried some editing in /etc/sysconfig/iptables but no luck.

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General :: Configure Centos 5.4 To Work As A Router And Firewall On Its Own?

Jun 15, 2011

how to setup centos to act as router and firewall at our office i just installed the os now i dont know where to go from here i have all the isp adresses,dns and gateway any assistance coz am really interested in learning linux thanxs iused some instructions on this site [URL] and when i try the /sysctl.config on my terminal now i get the message permission denied

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Red Hat / Fedora :: NTP In Virtual Server - Error; # /etc/init.d/ntpd Status Ntpd Dead

Apr 1, 2010

I am facing issue in ntp, it is getting killed frequently. see below error; # /etc/init.d/ntpd status ntpd dead but pid file exists After starting service it is works fine but again after sometimes it get in dead postition.

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Networking :: Configure My Firewall (through Iptables) To Allow Apt-get Features

Apr 26, 2010

I am encountering problems to configure my firewall (through iptables) to allow apt-get features, like update and install.I have the latest debian server running in a virtual machine in my windows xp and therefore I have two interfaces in this debian server:- NAT Interfaceinet: 10.0.2.15- Host Only Interfaceinet: 192.168.56.101So far my iptable rules drop all packets for default, in exception icmp and ssh that I allow to ping and connect from my windows xp. Both of them I use only the Host interface (192...) to connect to another 192... interface on my windows.

Those are working fine, but apt is not. I know, in this very moment it shouldn't. But I made a lot of attempts trying to configure the iptables allow connections through the 80 and 21 ports from/to NAT and Host. I think I made all possible combination (or not, because it didnt work). But I'm wondering if someone more experient can help me solve this problem.

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Networking :: Configure Proxy & Firewall On SuSE 11.4?

Apr 6, 2011

I need to restrict access to the internet and keep unwanted software out of LAN with 45 workstations at the school I teach at. I thought about configuring a proxy and firewall on SuSE 11.4?

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Ubuntu Networking :: Firewall Settings : Unable To Configure For Apt-get And Dns?

Mar 28, 2010

I have tried various rules, like opening port 53 for the DNS with little success. I finally figured that you need to set the source port to 53 and NOT the destination port.However, I have been unable to figure out what ports apt-get requires. The only way I get it to work is to accept everything in iptables.

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Networking :: Way To Configure Telnet Server Without Disable Firewall

Oct 13, 2010

I have a question about telnet.Is there any way to configure a telnet server without disable firewall.I am using redhat 5.2 and fedora 12.I have lack of knowledge about firewall.

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CentOS 5 :: How To Set Up NTPD Properly

Dec 16, 2009

I have a Windows 2003 server that runs a Win32 time server which synchronizes with off site time sources. I have a CentOS 5.4 server which I just configured and installed NTP on. For some reason, I keep getting time discrepancies even after the server is (apparently) synching with my local NTP server on the Windows box.

Hwclock is set to UTC true/etc/localtime is properly symlinked to appropriate /usr/share/zoneinfo fileNTPD is setup as a service which loads on startupNTP.conf is configured to only retrieve from my local Windows 2003 time serverntpq -p seems to verify that the system is indeed synching up properlyThe problem is, whenever I run the 'date' command it is displaying my system time in (presumably) UTC. That is, even though my the CentOS box appears to be synching up to the local time, it's not translating it into my proper time zone. Consequently, the date is always at -6 hours from the actual local time. It was my understanding that the hwclock is fine to remain at UTC as ntpd should be synching with my local Windows 2003 time server periodically and updating it, and the system time should be getting translated to my localtime.

what I do, after rebooting the box the hwclock and system clock display the improper time.Maybe I just have a fundamental misunderstanding of how this is supposed to operate.Update: I'm not sure why, but after I commented out the other servers and added a fudge declaration for my internal server and rebooted, everything is working as it should and the time is correct.I'm still not really sure if it was adding the "fudge <hostname> stratum 2" declaration that corrected things, or commenting out the additional hosts, so I'll leave this open if anyone cares to comment or contribute.

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CentOS 5 :: Ntpd -gq Not Working?

Aug 29, 2010

i'm trying to use the ntpd -gq instead of ntpdate. The result is that clock not set. as below. However ntpdate is working ok and had set the clock correctly.this is the ntp.conf file:

[root@CentOS5 ~]# cat /etc/ntp.conf
logfile /var/log/ntp.log
driftfile /var/lib/ntp/drift
server 0.centos.pool.ntp.org

this is the output of command:
[root@CentOS5 ~]# ntpd -dqg
ntpd 4.2.2p1@1.1570-o Sat Dec 19 00:58:16 UTC 2009 (1)[code]....

Also attached is the trace file, from the trace file, everything seems ok, timestamps is sent and received:

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CentOS 5 Networking :: Dnsmasq Not Starting Correctly?

Nov 2, 2009

Since latest large update to CentOS 5.3, which also upgraded to 5.4, I have problem with dnsmasq. CentOS is real server on real hardware (not virtual). I use dnsmasq as dhcp server as usual. On hardware startup or reboot, these lines are included in /var/log/messages

Nov 2 19:06:16 server avahi-daemon[2965]: New relevant interface eth0.IPv4 for mDNS.
Nov 2 19:06:16 server avahi-daemon[2965]: Joining mDNS multicast group on interface eth0.IPv4 with address 192.168.0.1.

[Code]....

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CentOS 5 :: Use NTPD To Keep The Time Correct On All Of The Virtual Machines?

Jan 27, 2009

I have a server running VMWare Server on it with 4 virtual machines running. I am trying to use NTPD to keep the time correct on all of the virtual machines. On my physical server, I have installed ntpd and this is it's config file:

Quote:# ntpd.conf
tinker panic 0
restrict 127.0.0.1
restrict default kod nomodify notrap
server 0.vmware.pool.ntp.org
server 1.vmware.pool.ntp.org
server 2.vmware.pool.ntp.org

[Code]...

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CentOS 5 :: Clock Time Jumps Into The Future (Xen + Ntpd)?

Nov 20, 2009

I'm having a problem with the time on one of my servers jumping forward into the future. We run serveral CentOS 5.4 servers running Xen, some up to date and some a little older. The one in question is running 2.6.18-164.el5xen, with xen-libs-3.0.3-94.el5_4.2 and xen-3.0.3-94.el5_4.2. On this server are several Xen virtual machines, also running CentOS 5.4 with kernel 2.6.18-164.el5xen. One in particular has problems with the clock keeping proper time.

We use NTP (ntpd) to sync time to a central server in the company. Our NTP set-up works fine, and we have problems on only a couple of servers out of many. The problem I see is that one one particular Xen virtual machine, the clock will suddenly jump forward into the future, usually by several minutes but once by more than an hour. This has obvious implications for software running on the machine. Software such as Oracle grid control agent will restart itself under the (incorrect) assumption that it has been hung for several minutes with no activity. Oracle database will cope gracefully, but applications that refer to the clock will be confused.

We detect these time jumps because we have Nagios checking the clock on each host against the centralised time server (Nagios's check_ntp plugin). Nagios will suddenly report a clock offset that is miles into the future. Following the time jump, ntpd on the host in question will re-sync the time. Ntpd keeps the time steady, ticking just a few milliseconds per second until real time catches up with the server. i.e. Nagios will report the time as being 10 minutes ahead, then a minute later the host will be 9 minutes ahead, and then a further minute later the host will be 8 minutes ahead of real time. The clock on the host stays running very slow until it eventually is correct.

[Code]...

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CentOS 5 Server :: Ntpd Startup Fails During Boot

Sep 1, 2010

ntpd startup fails during boot.Does startup just fine manually from command line once it's booted though. Any suggestions what I might adjust?

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Software :: CentOS 5.3 VM With Ntpd, No Server Suitable For Synchronization Found?

Jan 8, 2010

I cant get ntpd to synchronize with the ntp servers. I have a CentOS 5.3 32 bit Virtual Machine. I'm in USA on Pacific Standard Time. Here's all configuration and other important information for troubleshooting. Is there anything wrong with my config? btw, I used wireshark to look at the UDP packets - I dont get any responses from any of the servers back. I only see requests going out from my server, but no response. Is this a firewall Issue? If it is, then do I need to just enable UDP port 123 on the firewall?

[Code]...

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CentOS 5 Networking :: Firewall Insanity Iptables And Apf Don't Seem To Like Each Other?

Aug 13, 2009

I'm at my wits end at this point.

CentOS 5
iptables 1.4.1.1
APF 9.7
Webmin 1.4.80 (yes i can be a gui noob at times)

I'm currently running a dedicated server that hosts a couple of sites and runs a game server or two. I was using iptables on its own for a while, but recently I'm a target of all sorts of attacks (typically aimed directly at the gameserver on port 7777. UDP flood attacks, etc). I'm also seeing an spike in foreign spam, SSH brutes, and a few people in Turkey thought it would be cute to download files over and over and over I have decided to start banning entire countries, using the subnets listed here [URL]... I'm trying to block Central and South america (189,190,200,201.x.x.x), China, Ukraine, Turkey, Iran, Spain and Italy. I do this because a majority of the traffic from those areas are usually up to no good.

I installed APF so I could easily add these ranges in deny_hosts.rules and be done with it. I added the ranges, which turned out to be too many, and the system tanked. I decreased the amount of ranges to just 4:

189.0.0.0/8
190.0.0.0/8
200.0.0.0/8
201.0.0.0/8

Restarted APF and it loaded fine. Do an apf --list and iptables --list and it shows those 4 ranges as blocked. The only issue...I have people from 190.x and 200.x connecting to the gameserver and PLAYING. Its as if the firewall isnt there. Also, adding those ranges to /etc/hosts.deny (or whatever) doesn't block them either.

I add one of my own ips and I get blocked instantly. WTF?? I look in the iptables for webmin, and it shows an empty firewall. I do iptables --list and it shows the ranges I added in APF. I'm looking at building (or whatever its called) an fresh iptables with the geoip module added in. [URL]...

I've never done anything like this, and I don't want to kill the box. I also don't want to spend the effort if 1) something is wrong with my system to begin with and 2) the geoip module doesn't work. geoip module aside....how exactly should i configure the firewall? Empty iptables completely and then rely on APF for everything? Oh and heres another tidbit: I tried this before 2 years ago and it used to be that anything I put in APF would show when i looked at iptables using the webmin module. Thats no longer the case now. That was also on CentOS 4 when it did that. I don't know if moving to 5 is whats preventing it now.

In a nutshell, I'm new at this and I'm being inundated with terrible people trying to do terrible things and I'm ready to just give up. Can someone just give me a quick rundown on:

1) how to test that my firewall is actually firewalling

2) how I should configure the/a firewall on this CentOS5. Not too specific, I just want to know if I should empty iptables then load apf, should i not bother with APF (i like it when it works), is there a specific order of doing things?

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Networking :: Centos 5.2 Firewall / AccessPoint Using Atheros AR5212?

Jan 22, 2009

I've got a home firewall setup running CentOs 5.2. It's got two wired interfaces: inside and out and I'm successfully using iptables to filter and nat traffic in and out as expected. Recently I've added an AirLink101 AWLH4030 wireless nic that is recognized as the AR5212/AR5213 chipset. It appears that I have everything configured properly and I've eradicated every error encountered so far. Currently, I have my ath0 interface up and essid set but am unable to connect or even see the AP from my laptop. Here is a metric shit ton of debug/output for any networking gurus to ponder over:

Ethernet Devices:

Code:

alias lsEth='lspci -v | grep "Ethernet" -A 7'

Code:

lsEth
01:09.0 Ethernet controller: VIA Technologies, Inc. VT6105 [Rhine-III] (rev 86)
Subsystem: D-Link System Inc Unknown device 1406
Flags: bus master, stepping, medium devsel, latency 64, IRQ 209

[code]...

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CentOS 5 Networking :: Open The Firewall To Internal Network Card?

Jul 28, 2010

I have just installed CentOS and it is working fine!I made a masquerade with the document there: I didn't used the script, because right now, I do not completely understand it, and obviously I am not modifying anything by leaving it like that.I was using Mandriva before and I am used to graphical tools My questions are:I add the following lines in my iptables:

[root@localhost ~]# service iptables stop
[root@localhost ~]# iptables -t nat -A POSTROUTING -o eth1 -j MASQUERADE
[root@localhost ~]# service iptables save

[code]....

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Networking :: Setup Firewall / Sys1 Is Not Connected To Firewall For Testing Purpose?

May 18, 2010

I am learning to setup firewall in my home for that i have selected four system(sys1,sys2....sys4) for testing .I have configured sys2 to act as a firewall with two NIC. sys3 and sys4 are inside the firewall . sys1 is not connected to firewall for testing purpose.

the IP assignments are follows :

sys1 : ( fedora, not connected to firewall i am thinking, But i am not sure )

IP : 192.168.2.1 ,
gateway : blank
dns1 : blank
dns2 : blank

sys2 firewall ,IPTABLES )
code....

what happened is that sys1(not connected to firewall) can ssh to sys4(connected,inside firewall),since the rules are written not to ssh form sys1 to sys4..

then I came to know whatever the request I give, It directly goes as sys1 --> sys4. Not as sys1-----> sys2(firewall)---> sys4 .and the firewall is not filtering and processing anything for both inbound and outbound (i think it's my mistake some where). the requests are directly going inside without firewall.

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CentOS 5 Networking :: When I Change Dom0's Firewall Setup, The DomU Will Fail To Connect To Internet?

May 17, 2010

I'm using virtual network (NAT network) for my domU.When I change dom0's firewall setup, the domU will fail to connect to Internet anymore.So far, the only way to bring the network back is reboot dom0 !I try to restart service network and libvirtd on dom0 ... it doesn't work.How can I bring the domU network back without reboot dom0 ?

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Networking :: NTPD - No Server Suitable For Synchronization Found

Mar 29, 2011

I am having a situation with an NTPD server.

Code:
remote refid st t when poll reach delay offset jitter
plesk2.datacent .INIT. 16 u - 64 0 0.000 0.000 0.000
91.198.87.118.b .INIT. 16 u - 64 0 0.000 0.000 0.000
core.fr.zeroloo .INIT. 16 u - 64 0 0.000 0.000 0.000
178-26-105-100- .INIT. 16 u - 64 0 0.000 0.000 0.000
and it remains so no matter how long I wait...

Hoping to get better results with ntpdate, I stopped NTPS and tried :
Code:
# ntpdate ntp.skynet.be
29 Mar 09:12:26 ntpdate[4715]: no server suitable for synchronization found
# ntpdate -ud ntp.skynet.be
29 Mar 09:14:02 ntpdate[4814]: ntpdate 4.2.4p4@1.1520-o Sun Nov 22 16:14:35 UTC 2009 (1)
transmit(195.13.23.5)
receive(195.13.23.5) .....

I am running Debian Lenny 64b, and every packages are totally updated. I have 25 identical servers. And there is just one giving me this problem. From what I see, it is not a connection/FW issue since ntpdate get replies from the ntp server (ntp.skynet.be is my isp's stratum 2 ntp server).

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CentOS 5 Networking :: How To Configure VPN On CentOS 5.4 X86_64

Dec 29, 2009

I am brand new to this forum! I have spent some time on other Linux forums but based on my usage of CentOS I figured that it would be best to come straight to the pros. I've been using CentOS for a while now, mostly as a web server. Actually I use it as the base and installed Parallels Plesk Control Panel.

Anyway I want to setup a VPN and so far I haven't found any real solid documentation on how to do that! Yes I could install DAG/RPM Forge but what I really want to know how to do it from scratch. What I mean by scratch is that I want to download the tar.gz package from openvpn.net and then build it as required. I don't know much about building or compiling a package so that is why I have come here for help! I am guessing that I need to compile openVPN with openSSL and probably a few other packages... I could use openSWAN but I don't want to.

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Ubuntu :: Best Firewall In 10.10 - How To Configure

May 6, 2011

Which is the best firewall in ubuntu10.10 and how to configure it so that hackers do not get access to my computer, I also do use torrent.

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Ubuntu :: How To Configure Firewall On 10.10 Platform

Feb 27, 2011

How do I configure the firewall? Is there a firewall or do I have to install one? I cant find a app anywhere in the menu. Running 10.10

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Security :: Configure A Spare Pc As A Firewall?

Jul 16, 2010

How do I configure a spare pc as a firewall for my home and what distro would I use?

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OpenSUSE Network :: Correctly Configure Apache / Subversion And Mod_dav In 11.2

Feb 17, 2010

I have a problem to correctly configure apache / subversion and mod_dav in openSUSE 11.2 I have setup a virtual host on my home server (because I need to access it from the Internet), that should be a subversion server. The subversion root directory is the

Code:
/srv/svn/repos
I plan to use a separate directory for each project.
So, the svn tree will be/srv/svn/repos/project1/....
/srv/svn/repos/project2/....
/srv/svn/repos/project3/..

Apache serves the web pages (actually the directories) but since the documentroot and the SVN root are the same, it cannot handle the SVN repositories correctly. So, I re-read the Setting up a Subversion server using Apache2 - openSUSE how-to and followed it's suggestion. (Use a Location outside the document root) Anyway, the problem is that I have a 404 error, which of course is normal, since there is no alias set for the /rep location I use.

[Code]...

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Software :: Configure Irssi To Work Correctly After Having Used XChat For Quite Some Time?

Dec 31, 2010

I am trying to configure irssi to work correctly after having used XChat for quite some time. When I try to join #fedora on Freenode, however, I am unable to identify my username (which worked fine in XChat). Subsequently, I automatically join #fedora-unregistered (see http://pastebin.com/XUcx7CLe). I have edited the contents of the ~/.irssi/config file using /COMMAND in the irssi client (see http://pastebin.com/zV7NZYKG). I think these are the most relevant parts of the configuration file where the problem must lie.

Code:
{
address = "irc.freenode.net";
chatnet = "Freenode";
port = "6667";
use_ssl = "no";
ssl_verify = "no";
autoconnect = "yes";

[Code]...

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